There are conventional devices that carry out multi-step analytical procedures in an automated or semi-automated fashion. For example, microbiological analytical systems currently carry out automated antimicrobic susceptibility testing procedures using both photometric and fluorometric detection methods. The MicroScan Division of Baxter Healthcare Corporation sells a device of this type under the trade designation "Walk-Away." Armes et al. U.S. Pat. No. 4,676,951 and Hanaway U.S. Pat. Nos. 4,643,879 and 4,681,741 describe certain features the Walk-Away system.
The Walk-Away system, like other commercial systems, usually analyze many specimens at one time. When using photometry, this requires the establishment and use of multiple optical channels, one for each specimen undergoing analysis. Calibration and alignment of the multiple optical channels relative to each other and relative to the multiple specimens undergoing analysis are essential, if accurate and reproducible results are to be obtained.